tranny problems....

[91 k1500]

bad trans mount?  I would say you need a mid plate!

do you run a mid plate with rubber motor mounts or do ya solid mount the engine?

[Hammerlane]

sounds to me like you have some other issue (besides the above mentioned obvious reasons)
alignment or movement of some type issue (bad rubber bushings.. ie trans, t-case,engine, mount etc...)

driving style (seriously) are you launching the truck and staying on the throttle?
it appears to be "shock load" damage of some type..
Motor/ HP rating.. what type of setup do you have?

is your jackshaft (small drive shaft between trans and t-case) a slip yolk style or solid?

[91 k1500]

its a 355 with vortec heads and a decent cam.... probably around 350hp running stock motor mounts 2wd turbo 350 trans, 3000 stall.... I had a little drive shaft running from the trans to the divorced 205 and I think it bound and broke.... the truck was out of the hole and climbing a wet bank.... not sure if it found dry dirt or what.. it just made a big bang and that was the end of it. it broke the ujoint at the t case and the drive shaft beat the hell out of the floor for a sec broke the tail shaft housing and then  ejected its self from the trans.....
I am gonna look the tranny mount over real good when I get home. I have since built a new drive shaft using 1350 u joints and yokes......

[91 k1500]

I am using the slip yoke that goes into the trans housing..... if that makes sense.....

[Hammerlane]

its a 355 with vortec heads and a decent cam.... probably around 350hp running stock motor mounts 2wd turbo 350 trans, 3000 stall.... I had a little drive shaft running from the trans to the divorced 205 and I think it bound and broke.... the truck was out of the hole and climbing a wet bank.... not sure if it found dry dirt or what.. it just made a big bang and that was the end of it. it broke the ujoint at the t case and the drive shaft beat the hell out of the floor for a sec broke the tail shaft housing and then  ejected its self from the trans.....
I am gonna look the tranny mount over real good when I get home. I have since built a new drive shaft using 1350 u joints and yokes......

Ok, to start.. part of the issue is the 2wd trans case.. a 4wd case is thicker in the bell housing area.. (for this very reason).
additional damage to the bell housing probably came from the release of torque,, when the Ujoint failed you were torqed up (on the throttle) and when it failed... all the torque was released almost instantly..

but it still sounds to me like you have a worn bushing issue too..

[Hammerlane]

I am using the slip yoke that goes into the trans housing..... if that makes sense.....

how much travel do you have in the yolk?? I've seen driveshaft damage due to bottoming out a slip yolk,, if your t-case or other components are moving.. and you bottom it out it will take a yolk out right now.

[91 k1500]

I think the yoke is three inches.... I have it set to run right in the middle.... so about 1.5 inches sticking out....
the t case mount is welded to the chassis and the t-case is solid mounted to the cross member... should the t case be rubber mounted?

should I step up to a th400?

[Hammerlane]

I think the yoke is three inches.... I have it set to run right in the middle.... so about 1.5 inches sticking out....
the t case mount is welded to the chassis and the t-case is solid mounted to the cross member... should the t case be rubber mounted?

should I step up to a th400?

need to find out the reason for the damage first.. your running the same setup as I am (except no divorced case for me)
and I dont have these issues..
my front driveshaft has broken a few times on me by bottoming out,, a buddy helped me build a new front shaft and we:

measured twice, cut once.. but the splines on the shaft are right at the end of the slip yolk, not enough to be seen.. but right there at the end of the yolk.. since then, no breakage for me, and I launch my truck.  this allows for maximum travel.

solid mounted t-case and rubber mounted motor/trans could be an issue like Mudbuster said.  if this is in the 1500, 1/2ton frames flex ALOT.. and with a solid mounted t-case and less than 1.5 inches of travel, and multiple breaks... hmmmmm
the possibility of a broken motor or trans mount still exists too, need to check those out real good first.

[91 k1500]

i will look it over real good when we drag it back into the garage.... I appreciate the help, it would be nice to make it a whole day with out breaking it! lol 

[BIG DOG]

YOU DO HAVE A LONG SHAFT THAT GOES FROM T-CASE TO BELL HOUSING  LIKE THE STABILIZER BAR         DID YA FIND THAT CRACK WHEN YOU CHECK TORQUE BOLTS
IT PULLED TORQUE OFF THE SHAFT     

[91 k1500]

its a divorcedt-case so it does not mount to the trans..... I found the crack when I was taking the bell housing bolts out to pull the trans. ...

[RIP_K52007]

well that narrows it down to heavy foot and/or truck landing wrong??? lol... could proly take it to a buider n get yourses guts stuck in a dif. case for cheaper than rebuilding.. as long as nothing internal is too messed up...